One way check valves, duckbill valves and other types of flow regulation apparatuses have been known in the art for a variety of applications. For example, U.S. Pat. Nos. 3,901,272, 4,535,818 and 4,060,184 show duckbill check valves. Duckbill valves typically include a housing into which a resilient flow regulator is mounted. These valves usually consist of a slitted opening or lips which are arranged in a converging relationship from an open end to a normally closed, slitted end. The slitted opening is normally closed by a higher fluid pressure level existing outside of the duckbill-like portion than inside. When, however, the fluid pressure is greater internally, rather than externally, the closed slitted position will then open, thus permitting the free passage of a fluid such as air to the normally closed side of the duckbill valve.
The duckbill check valves disclosed U.S. Pat. Nos. 3,901,272 and 4,060,184 are opened by penetrating and opening the lips via the open-ended portion of the duckbill valve by a tapered rod and wire member, respectively.
U.S. Pat. Nos. 3,351,081 and 4,176,681 disclose air inflation valves opened against the force of a compression spring by inflating air pressure. These valves are held closed by back pressure and thus operate as check valves. Deflation may be accomplished by depressing an actuator to open the valves.
Although the aforementioned valves generally operate satisfactorily, these valves do not, in fact, provide a combined duckbill check valve and pressure relief valve apparatus. Furthermore, these valves are not equipped with a tamper-proof, push-button mechanism whereby the user may release the pressure of a fluid easily by depressing, with his or her finger, a valve actuator to permit a controlled amount of backflow of a given fluid or deflation of an inflated member, for example.